Fan blade with internal shear-thickening fluid damping

ABSTRACT

An airfoil for use in a gas turbine engine is formed to define a cavity formed in the airfoil. The airfoil further includes at least one obstructing member arranged within the cavity and a shear-thickening fluid disposed in the cavity. A viscosity of the shear-thickening fluid increases in response to the airfoil experiencing an aeromechanic response or vibrations such that the obstruction of the movement of the thicker fluid by the obstructing member dampens the vibrations of the airfoil and reduces negative effects of a dynamic response of the airfoil.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Embodiments of the present disclosure were made with government supportunder Contract No. FA865019F2078 awarded by the U.S. Air Force. Thegovernment may have certain rights.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to propulsion systems, and morespecifically to airfoils for use in propulsion systems.

BACKGROUND

Propulsion systems may be used to power aircraft, watercraft, powergenerators, and the like. Propulsion systems may include gas turbineengines, electrically driven engines, hybrid configurations, and othersimilar designs. Gas turbine engines in particular typically include acompressor, a combustor, and a turbine. The compressor compresses airdrawn into the engine and delivers high pressure air to the combustor.In the combustor, fuel is mixed with the high-pressure air and isignited. Products of the combustion reaction in the combustor aredirected into the turbine where work is extracted by rows of rotatingblades and non-rotating vanes to drive the compressor and, sometimes, anoutput shaft. Each blade and vane has an airfoil that interacts withgases as they pass through the engine.

Airfoils have natural vibration modes of increasing frequency andcomplexity of the mode shape. The simplest and lowest frequency modesare typically considered to be the bending modes and the torsion mode.The first bending mode is a motion normal to the working surface of anairfoil in which the entire space of the airfoil moves in the samedirection. Subsequent bending modes are similar to the initial bendingmodes, but with a node line of zero motion somewhere along the span ofthe airfoil other than the root, so that the upper and lower portions ofthe airfoil may move in opposite directions. The first torsion mode is atwisting motion around an axis that is parallel to the span of theairfoil, in which the entire space of the airfoil, on either side of theaxis moves in the same direction.

Blades and vanes may be subject to destructive vibrations induced bysteady or unsteady interaction of the airfoils of those blades and vaneswith gases passing through a gas turbine engine. One type of vibrationis flutter, which is an aero-elastic instability resulting frominteraction of the flow over blades and the natural vibrationtendencies. The lowest frequency vibration modes, i.e., the firstbending mode and the first torsion mode, are often the vibration modesthat are susceptible to flutter. When flutter occurs, the unsteadyaerodynamic forces on the blade, due to its vibrational inherentattributes and insufficient mechanical or aerodynamic damping, addenergy to the vibration, causing the vibration amplitude to increase.The vibration amplitude can become large enough to cause damage to ablade. Another type of vibration, which may occur in blades or vanes, isknown as forced response, which is an aero-elastic response to inletdistortion or wakes from upstream airfoils, struts, or any other flowobstruction. The operable range, in terms of pressure rise and flowrate, of turbomachinery can sometimes be restricted by flutter andforced response phenomena.

SUMMARY

The present disclosure may comprise one or more of the followingfeatures and combinations thereof.

An airfoil for use in a gas turbine engine according to the presentdisclosure includes an airfoil body and at least one obstructing member.The airfoil body extends radially outwardly relative to an axis andconfigured to interact with gases surrounding the airfoil body, theairfoil body having a leading edge, a trailing edge opposite the leadingedge, a pressure side, and a suction side opposite the pressure side,the airfoil body formed to define a cavity within the airfoil body, thecavity being defined by a radially outer top surface, a radially innerbottom surface, a first inner side surface, a second inner side surface,a pressure side inner surface, and a suction side inner surface, theairfoil body including a shear-thickening fluid disposed within thecavity, wherein a viscosity of the shear-thickening fluid increases inresponse to the airfoil experiencing at least one of an aeromechanicresponse and vibrations during use of the airfoil.

In some embodiments, the at least one obstructing member is arrangedwithin the cavity and fixed to the airfoil body to obstruct movement ofthe shear-thickening fluid within the cavity in response to theviscosity of the shear-thickening fluid increasing so as to dampen thevibrations of the airfoil and reduce negative effects of a dynamicresponse of the airfoil.

In some embodiments, the at least one obstructing member includes aplurality of pegs that each extend from the pressure side inner surfaceto the suction side inner surface of the cavity.

In some embodiments, the plurality of pegs includes at least two rows ofpegs, each row including at least two pegs. Each row of pegs of the atleast two rows of pegs extends from the leading edge to the trailingedge in a direction generally axially relative to the axis. Each row ofpegs of the at least two rows of pegs is spaced apart from an adjacentrow of pegs in a radially direction.

In some embodiments, the at least one obstructing member includes aplurality of radially extending walls, the plurality of radiallyextending walls including at least one first wall that extends radiallyoutwardly away from the radially inner bottom surface towards theradially outer top surface of the cavity, the at least one first wallextending partway from the radially inner bottom surface towards theradially outer top surface of the cavity, the plurality of radiallyextending walls further including at least one second wall that extendsradially inwardly away from the radially outer top surface towards theradially inner bottom surface of the cavity, the at least one secondwall extending partway from the radially outer top surface towards theradially inner bottom surface of the cavity.

In some embodiments, the at least one first wall extends generallyperpendicularly away from the radially inner bottom surface of thecavity and the at least one second wall extends generallyperpendicularly away from the radially outer top surface of the cavity.Each wall of the at least one first wall and the at least one secondwall includes a terminal end. The plurality of radially extending wallsalternate between the at least one first wall and the at least onesecond wall in a direction from the leading edge to the trailing edge.Each wall of the at least one first wall extends radially beyond aterminal end of an adjacent second wall of the at least one second wall.

In some embodiments, the at least one obstructing member includes aplurality of angled walls, the plurality of angled walls including atleast one first angled wall that extends away from the first inner sidesurface of the cavity towards the radially inner bottom surface and thesecond inner side surface, the at least one first angled wall extendingat a first angle relative to the first inner side surface and extendingpartway from the first inner side surface of the cavity towards theradially inner bottom surface and the second inner side surface, theplurality of angled walls further including at least one second angledwall that extends away from the second inner side surface of the cavitytowards the radially outer top surface and the first inner side surface,the at least one second angled wall extending at the first anglerelative to the first inner side surface and extending partway from thesecond inner side surface of the cavity towards the radially outer topsurface and the first inner side surface such that each first angledwall is parallel to each second angled wall.

In some embodiments, each angled wall of the at least one first angledwall and the at least one second angled wall includes a terminal end.The plurality of angled walls alternate between the at least one firstangled wall and the at least one second angled wall in a direction fromthe radially inner bottom surface to the radially outer top surface ofthe cavity. Each angled wall of the at least one first angled wallextends beyond a terminal end of an adjacent second angled wall of theat least one second angled wall.

In some embodiments, the at least one obstructing member includes a meshgrid, the mesh grid formed by a first plurality of rods extending fromthe first inner side surface to the second inner side surface and asecond plurality of rods extending from the radially inner bottomsurface to the radially outer top surface. The mesh grid suction side isspaced apart from the suction side inner surface of the cavity and themesh grid pressure side is spaced apparat from the pressure side innersurface of the cavity.

In some embodiments, the first inner side surface of the cavity islocated adjacent the leading edge of the airfoil body and the secondinner side surface of the cavity is located adjacent the trailing edgeof the airfoil body. The radially inner bottom surface is locatedradially inwardly of a halfway point of a radial extent of the airfoilbody. The at least one obstructing member includes a plurality of angledwalls, the plurality of angled walls including at least one first angledwall that extends away from the first inner side surface of the cavitytowards the radially inner bottom surface and the second inner sidesurface, the at least one first angled wall extending at a first anglerelative to the first inner side surface and extending partway from thefirst inner side surface of the cavity towards the radially inner bottomsurface and the second inner side surface, the plurality of angled wallsfurther including at least one second angled wall that extends away fromthe second inner side surface of the cavity towards the radially outertop surface and the first inner side surface, the at least one secondangled wall extending at the first angle relative to the first innerside surface and extending partway from the second inner side surface ofthe cavity towards the radially outer top surface and the first innerside surface such that each first angled wall is parallel to each secondangled wall.

In some embodiments, the at least one obstructing member includes aplurality of ridges, the plurality of ridges including at least onefirst ridge extending away from the pressure side inner surface of thecavity and at least one second ridge extending away from the suctionside inner surface of the cavity. Each ridge of the at least one firstridge and the at least one second ridge includes a terminal end. Theplurality of ridges alternate between the at least one first ridge andthe at least one second ridge in a direction from the leading edge tothe trailing edge. Each ridge of the at least one first ridge extendsbeyond a terminal end of an adjacent second ridge of the at least onesecond ridge in a direction from the pressure side to the suction side.

In some embodiments, the airfoil body includes an airfoil root and anairfoil tip spaced apart radially outward from the airfoil root, and theradially outer top surface of the cavity is located adjacent to theairfoil tip.

In some embodiments, the cavity is arranged radially outwardly of ahalfway point of a radial extent of the airfoil body.

A rotor assembly for use in a gas turbine engine according to a furtheraspect of the present disclosure includes a wheel arrangedcircumferentially about an axis and a first airfoil having a firstairfoil body and at least one first obstructing member. The firstairfoil body extends radially outwardly relative to an axis andconfigured to interact with gases surrounding the first airfoil body,the first airfoil body having a leading edge, a trailing edge oppositethe leading edge, a pressure side, and a suction side opposite thepressure side, the first airfoil body formed to define a first cavitywithin the first airfoil body, wherein the first cavity is defined by aradially outer top surface, a radially inner bottom surface, a firstinner side surface, a second inner side surface, a pressure sidesurface, and a suction side surface, the first airfoil body including afirst shear-thickening fluid disposed within the first cavity, wherein aviscosity of the first shear-thickening fluid increases in response tothe first airfoil experiencing at least one of an aeromechanic responseand vibrations during use of the airfoil.

In some embodiments, the at least one first obstructing member arrangedwithin the first cavity and configured to obstruct movement of the firstshear-thickening fluid within the first cavity in response to theviscosity of the first shear-thickening fluid increasing so as to dampenthe vibrations of the first airfoil and reduce negative effects of adynamic response of the first airfoil.

In some embodiments, the at least one first obstructing member includesa plurality of pegs that each extend from the pressure side innersurface of the first cavity to the suction side inner surface of thefirst cavity.

In some embodiments, the at least one first obstructing member includesa plurality of radially extending walls, the plurality of radiallyextending walls including at least one first wall that extends radiallyoutwardly away from the radially inner bottom surface towards theradially outer top surface of the first cavity, the at least one firstwall extending partway from the radially inner bottom surface towardsthe radially outer top surface of the first cavity, the plurality ofradially extending walls further including at least one second wall thatextends radially inwardly away from the radially outer top surfacetowards the radially inner bottom surface of the first cavity, the atleast one second wall extending partway from the radially outer topsurface towards the radially inner bottom surface of the first cavity.

In some embodiments, the at least one first obstructing member includesa plurality of axially extending walls, the plurality of axiallyextending walls including at least one first wall that extends away fromthe first inner side surface towards the second inner side surface ofthe first cavity, the at least one first wall extending partway from thefirst inner side surface towards the second inner side surface of thefirst cavity, the plurality of axially extending walls further includingat least one second wall that extends away from the second inner sidesurface towards the first inner side surface of the second cavity, theat least one second wall extending partway from the second inner sidesurface towards the first inner side surface of the first cavity, the atleast one first wall extends generally perpendicularly away from thefirst inner side surface of the first cavity and the at least one secondwall extends generally perpendicularly away from the second inner sidesurface of the first cavity.

In some embodiments, the rotor assembly further includes a secondairfoil circumferentially offset from the first airfoil relative to thewheel, the second airfoil extending radially outwardly from the wheelrelative to the axis and configured to interact with gases surroundingthe second airfoil. The second airfoil includes a second airfoil bodyand at least one second obstructing member.

In some embodiments, the second airfoil body extends radially outwardlyrelative to an axis and configured to interact with gases surroundingthe second airfoil body, the second airfoil body having a leading edge,a trailing edge opposite the leading edge, a pressure side, and asuction side opposite the pressure side, the second airfoil body formedto define a second cavity within the second airfoil body, wherein thesecond cavity is defined by a radially outer top surface, a radiallyinner bottom surface, a first inner side surface, a second inner sidesurface, a pressure side surface, and a suction side surface, the secondairfoil body including a second shear-thickening fluid disposed withinthe second cavity, wherein a viscosity of the second shear-thickeningfluid increases in response to the second airfoil experiencing at leastone of an aeromechanic response and vibrations during use of theairfoil.

In some embodiments, the at least one second obstructing member isarranged within the second cavity and configured to obstruct movement ofthe second shear-thickening fluid within the second cavity in responseto the viscosity of the second shear-thickening fluid increasing so asto dampen the vibrations of the second airfoil and reduce negativeeffects of a dynamic response of the second airfoil.

In some embodiments, at least one of (i) the at least one firstobstructing member is at least one of a different shape than the atleast one second obstructing member and oriented in a differentdirection than the at least one second obstructing member and (ii) afirst volume of the first shear-thickening fluid disposed in the firstcavity is different than a second volume of the second shear-thickeningfluid disposed in the second cavity so as to mistune adjacent airfoilsof the rotor assembly and mitigate flutter of the airfoils.

In some embodiments, the at least one first obstructing member includesa first plurality of walls and the at least one second obstructingmember includes a second plurality of walls, the first plurality ofwalls extend in a first direction, wherein the second plurality of wallsextend in a second direction, and the first direction is different thanthe second direction.

In some embodiments, the first cavity is filled with a first volume offirst shear-thickening fluid and the second cavity is filled with asecond volume of second shear-thickening fluid, and wherein the firstvolume is different than the second volume.

According to a further aspect of the present disclosure, a methodincludes providing an airfoil body having a leading edge, a trailingedge opposite the leading edge, a pressure side, and a suction sideopposite the pressure side, forming a cavity within the airfoil body,filling the cavity with a shear-thickening fluid, wherein a viscosity ofthe shear-thickening fluid increases in response to the airfoilexperiencing at least one of an aeromechanic response and vibrationsduring use of the airfoil, and arranging at least one obstructing memberwithin the cavity that is configured to obstruct movement of theshear-thickening fluid within the cavity in response to the viscosity ofthe shear-thickening fluid increasing so as to dampen the vibrations ofthe airfoil and reduce negative effects of a dynamic response of theairfoil.

These and other features of the present disclosure will become moreapparent from the following description of the illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutaway view of a gas turbine engine that includes a fan, acompressor, a combustor, and a turbine, the fan having a rotor includinga wheel arranged around an axis of the engine and a plurality of bladesor airfoils arranged around the wheel that each extend radially outwardfrom the wheel to interact with gases flowing through the engine andsuggesting that at least some of the airfoils formed as shown in FIG. 2to include a cavity formed therein, the cavity having at least oneobstruction arranged therein, and showing that the cavity contains ashear-thickening fluid configured to increase in viscosity when theairfoil experiences vibrations, where the movement of the thicker fluidagainst the obstruction and the sides of the cavity damp vibrations ofthe airfoil;

FIG. 2 is a cross-sectional view of one of the airfoils of FIG. 1showing that the cavity is arranged generally radially outwardly withinthe airfoil and that the shear-thickening fluid is disposed within thecavity, and showing that the at least one obstructing member includes aplurality of pegs that each extend from a pressure side inner surface tothe suction side inner surface of the cavity;

FIG. 3 is a top cross-sectional view of the airfoil of FIG. 2 showingthat the plurality of pegs are spaced apart in a direction from theleading edge to the trailing edge of the airfoil and that each pegextends from a pressure side inner surface to a suction side innersurface of the cavity;

FIG. 4 is a cross-sectional view of another embodiment according to thepresent disclosure of one of the airfoils of FIG. 1 showing that thecavity is arranged generally radially outwardly within the airfoil andthat the shear-thickening fluid is disposed within the cavity, andshowing that the at least one obstructing member includes a plurality ofradially extending walls, where some of the walls extend from a radiallyinner bottom surface of the cavity and some of the walls extend from aradially outer top surface of the cavity, and showing that the wallsthat extend from the bottom surface alternate with the walls that extendfrom the top surface;

FIG. 5 is a top cross-sectional view of the airfoil of FIG. 4 showingthat the plurality of radially extending walls are spaced apart in adirection from the leading edge to the trailing edge of the airfoil andthat each wall extends from the pressure side inner surface to thesuction side inner surface of the cavity;

FIG. 6 is a cross-sectional view of another embodiment according to thepresent disclosure of one of the airfoils of FIG. 1 showing that thecavity is arranged generally radially outwardly within the airfoil andthat the shear-thickening fluid is disposed within the cavity, andshowing that the at least one obstructing member includes a plurality ofradially extending walls, where some of the walls extend at an anglefrom a first inner side surface of the cavity near the leading edge ofthe airfoil and some of the walls extend at an angle from a second innerside surface of the cavity near the trailing edge of the airfoil, andshowing that the walls that extend from the first inner side surfacealternate with the walls that extend from the second inner side surface;

FIG. 7 is a cross-sectional view of another embodiment according to thepresent disclosure of one of the airfoils of FIG. 1 showing that thecavity is arranged generally radially outwardly within the airfoil andthat the shear-thickening fluid is disposed within the cavity, andshowing that the at least one obstructing member includes a mesh grid,the grid being formed by a plurality of rods or wires extending in twodirections, typically one direction from the leading edge to thetrailing edge and another direction from the radially outer top surfaceto the radially inner bottom surface, which therefore separates thepressure side from the suction side.

FIG. 8 is a top cross-sectional view of the airfoil of FIG. 7 showingthat a first group of rods or wires extend from the leading edge surfaceto the trailing edge surface of the cavity, and that a second group ofrods or wires extend in the direction from the radially inner bottomsurface to the radially outer top surface and terminate before touchingeither the pressure side inner surface to the suction side surface;

FIG. 9 is a cross-sectional view of another embodiment according to thepresent disclosure of one of the airfoils of FIG. 1 showing that thecavity occupies a majority of the radial extent within the airfoil andthat the shear-thickening fluid is disposed within the cavity, andshowing that the at least one obstructing member includes a plurality ofradially extending walls, where some of the walls extend at an anglefrom the first inner side surface of the cavity near the leading edge ofthe airfoil and some of the walls extend at an angle from the secondinner side surface of the cavity near the trailing edge of the airfoil,and showing that the walls that extend from the first inner side surfacealternate with the walls that extend from the second inner side surface;

FIG. 10 is a cross-sectional view of another embodiment according to thepresent disclosure of the airfoils of FIG. 1 showing that the cavity isarranged generally radially outwardly within the airfoil and that theshear-thickening fluid is disposed within the cavity, and showing thatthe at least one obstructing member includes a plurality of walls thatextend in the direction from the first inner side surface to the secondinner side surface of the cavity and vice versa, where some of the wallsextend generally perpendicularly away from the first inner side surfaceof the cavity and some of the walls extend generally perpendicularlyaway from the second inner side surface of the cavity, and showing thatthe walls that extend from the first inner side surface alternate withthe walls that extend from the second inner side surface;

FIG. 11 is a top cross-sectional view of another embodiment according tothe present disclosure of the airfoils of FIG. 1 showing that the cavityextends from the pressure side external surface to the suction sideexternal surface and that the shear-thickening fluid is disposed withinthe cavity, and showing that the at least one obstructing memberincludes a plurality of ridges that extend radially, where some of theridges extend from the pressure side inner surface and some of theridges extend from the suction side surface, showing that the ridgesthat extend from the pressure side inner surface alternate with thewalls that extend from the suction side surface, and showing that ridgesdo not contact the opposing surface to allow for movement of the fluidbetween the ridges;

FIG. 12 is a top cross-sectional view of another embodiment according tothe present disclosure of the airfoils of FIG. 1 showing that the cavityextends from the pressure side external surface to the suction sideexternal surface and that the shear-thickening fluid is disposed withinthe cavity, and showing that the at least one obstructing memberincludes a plurality of walls with orifices formed therein, and showingthat the walls extend at an angle from the pressure side inner surfaceand from the suction side surface, and showing that the location of theorifices in adjacent walls are staggered along a longitudinal extent ofthe walls;

FIG. 13 is a top cross-sectional view of another embodiment according tothe present disclosure of the airfoils of FIG. 1 showing that the cavityextends from the pressure side external surface to the suction sideexternal surface and not entirely to the leading edge and the trailingedge of the airfoil, showing that the shear-thickening fluid is disposedwithin the cavity, showing that the at least one obstructing memberincludes a mesh grid, and showing that the mesh grid is curved in adirection from the leading edge surface to the trailing edge surface ofthe cavity;

FIG. 14 is a top cross-sectional view of another embodiment according tothe present disclosure of the airfoils of FIG. 1 showing that the cavityextends from the pressure side external surface to the suction sideexternal surface and that the shear-thickening fluid is disposed withinthe cavity, showing that the at least one obstructing member includes aplurality of mesh grids, and showing that the mesh grids are spacedapart in a direction from the leading edge surface to the trailing edgesurface of the cavity and extend from the pressure side inner surface tothe suction side surface;

FIG. 15 is a side cross-section viewed in a direction from the leadingedge to the trailing edge of another embodiment according to the presentdisclosure of the airfoils of FIG. 1 showing that the cavity extendsfrom the pressure side external surface to the suction side externalsurface and that the shear-thickening fluid is disposed within thecavity, and showing that the at least one obstructing member includes aplurality of ridges that extend in the direction from the leading edgeto the trailing edge, where some of the ridges extend from the pressureside inner surface and some of the ridges extend from the suction sidesurface, showing that the ridges that extend from the pressure sideinner surface alternate with the walls that extend from the suction sidesurface, and showing that ridges do not contact the opposing surface toallow for movement of the fluid between the ridges;

FIG. 16 is a front cross-sectional view of another embodiment accordingto the present disclosure of a plurality of the airfoils of FIG. 1showing that the airfoils are arranged circumferentially around acentral axis of the gas turbine engine in an outlet guide vane assembly;

FIG. 17 is a front cross-sectional view of another embodiment accordingto the present disclosure of a plurality of the airfoils of FIG. 1showing that the airfoils are arranged circumferentially around acentral axis of the gas turbine engine in a rotor assembly as fanblades;

FIG. 18 is a cross-sectional view of a plurality of the airfoils of FIG.4 showing that adjacent airfoils include the same obstructing member anddiffering levels of shear-thickening fluid in their respective cavities;

FIG. 19 is a cross-sectional view of a plurality of the airfoils ofFIGS. 2, 4, and 6 showing that adjacent airfoils include the same levelsof shear-thickening fluid in their respective cavities and differentobstructing members arranged in their respective cavities; and

FIG. 20 is a cross-sectional view of a plurality of the airfoils of FIG.4 showing that a first airfoil includes shear-thickening fluid in itsrespective cavity and an adjacent second airfoil includes an epoxymaterial filling the entirety of its respective cavity.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to a number of illustrativeembodiments illustrated in the drawings and specific language will beused to describe the same.

A bladed rotor assembly 10 includes a plurality of airfoils 16 formed asblades as shown in FIG. 1 . In the illustrative embodiment, the bladedrotor assembly 10 is adapted for use in a gas turbine engine 110 thatincludes a compressor 112, a combustor 113, and a turbine 114, and a fan115 as shown in FIG. 1 . In other embodiments, the bladed rotor assembly10 and the vane assembly 70 described below may be utilized in anelectrically driven propulsion system, a hybrid propulsion system, orthe like. The fan 115 is driven by the turbine 114 and provides thrustfor propelling an aircraft. The compressor 112 compresses and deliversair to the combustor 112. The combustor 113 mixes fuel with thecompressed air received from the compressor 112 and ignites the fuel.The hot, high-pressure products of the combustion reaction in thecombustor 113 are directed into the turbine 114 to cause the turbine 114to rotate about an axis 11 of the gas turbine engine 110 and drive thecompressor 113 and the fan 115. In the illustrative embodiment, the fan115 includes the rotor 10.

The rotor 10 includes a wheel 12 and the plurality of airfoils 16 formedas blades as shown in FIG. 1 . The wheel 12 is arranged around the axis11. The airfoils 16 may each be comprised of a first material and arearranged around the wheel 12. Each airfoil 16 extends radially outwardlyaway from the wheel 12 relative to the axis 11 to interact with gasessurrounding the rotor 10. The first material is a metallic material inthe illustrative embodiment. In the illustrative embodiment, the gasturbine engine 110 may further include a vane assembly 70, in particularan outlet guide vane assembly, arranged in the fan exit 116 of theengine 110 as shown in FIG. 1 .

The bladed rotor assembly 10 and/or the vane assembly 70 may include oneor more of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916,1016, 1116, 1216 described below. In some embodiments, the bladed rotorassembly 10 and/or the vane assembly 70 includes only the airfoils 16.In some embodiments, the bladed rotor assembly 10 and/or the vaneassembly 70 may include any combination of groups of airfoils describedin alternative embodiments of the airfoils described herein. Forexample, as shown in FIG. 19 , the bladed rotor assembly 10 may includeat least one airfoil 16, at least one airfoil 116, and at least oneairfoil 216. Each of the airfoils 16, 116, 216, 316, 416, 516, 616, 716,816, 916, 1016, 1116, 1216 described herein have external surfaces thatare similarly sized and shaped for the particular gas turbine engine110.

Excessive dynamic responses may be a common aerodynamic phenomenon thatmay lead to excessive vibratory stress and eventual failure in bladesand vanes. For example, flutter in blades and intake distortion, mayoccur in blades and vanes. Reducing these phenomena may be difficultwhen combined with other requirements of the airfoils 16, such asstructural strength and aerodynamic performance. In some instances,mistuning blades may include changing the existing airfoil shape of someof the blades about the rotor. Yet, such arrangements may causeconflicting issues with the other original blades, such as forcedresponse.

In order to dampen the airfoil vibrations and thus reduce the negativeeffects of the dynamic response of the airfoil 16, the presentdisclosure provides for airfoils 16 having similar external shapes andhaving a cavity 22 formed therein. The cavity 22 includes at least oneobstructing member 28 arranged therein that is configured to obstructmovement of a fluid 30 disposed within the cavity 22. In theillustrative embodiments, the fluid may be a shear-thickening fluid ornon-Newtonian fluid which increases in viscosity in response toexperiencing vibrations. When the airfoil 16 experiences dynamicresponses such as those discussed above, the viscosity of theshear-thickening fluid 30 increases and thus increasing the difficultlyof the shear-thickening fluid 30 to move past or around the at least oneobstructing member 28. This behavior of the fluid 30, as well as thefluid 30 interacting with the inner walls of the cavity 22, dampens theairfoil vibrations and thus reduces the negative effects of the dynamicresponse of the airfoil 16.

The cavity 22 of the illustrative embodiment is partially filled withthe shear-thickening fluid 30 as shown in FIG. 2 . The extent to whichthe cavity 22 is filled with fluid 30 is dependent on the desireddamping effect. The remainder of the cavity space may be filled with airor other gas.

The airfoil 16 according a first embodiment of the present disclosureincludes an airfoil body 20 as shown in FIGS. 2 and 3 . The airfoil body20 has an aerodynamic shape for accelerating air through the gas turbineengine 110. The airfoil body 20 further includes an airfoil tip 21spaced apart radially outward from an airfoil root 23, the airfoil root23 located adjacent to the wheel 12, 1212 in embodiments in which theairfoil 16 is utilized in a bladed rotor assembly 10, fan blisk 1210, asshown in FIG. 17 . In embodiments in which the airfoil 16 is utilized ina vane assembly 70, the tip 21 may be located adjacent an outer platform1172 and the root 23 may be located adjacent an inner platform 1174, asshown in FIG. 16 . The airfoil body 20 has a leading edge 25, a trailingedge 27 opposite the leading edge 25, a pressure side external surface24, and a suction side external surface 26 opposite the pressure side 24as shown FIGS. 2 and 3 .

In the bladed rotor assembly 10 embodiment, the airfoil root 23 of theairfoil 16 is shaped to be received in a corresponding slot in the wheel12 to couple the airfoil 16 to the wheel 12. In some embodiments, theairfoil root 23 may be another suitable attachment method. In otherembodiments, the rotor 10 is a blisk and the plurality of airfoils 16,as well as the additional arrangements of airfoils described herein, areintegrally formed with the wheel 12.

The airfoil 16 is formed to include a cavity 22 within the airfoil body20 as shown in FIGS. 2 and 3 . Specifically, the first cavity 22 islocated radially outward of the airfoil 16 and adjacent to the tip 21.The cavity 22 is formed as hollowed-out space within the airfoil body20. In the illustrative embodiment, the cavity 22 is formed generallycentrally relative to the pressure side external surface 24, the suctionside external surface 26, the leading edge 25, and the trailing edge 27.In some embodiments, the airfoil body 20 may include more than onecavity based on the operating conditions that the airfoil 16 will beexperiencing. Moreover, in some embodiments, the cavity 22 may includesupport walls arranged therein to support the walls of the cavity 22.The cavity 22 is entirely sealed within the airfoil body 20. That is,the cavity 22 is covered entirely by metallic material that forms theairfoil body 20.

The cavity 22 is defined by a radially outer top surface 31, a radiallyinner bottom surface 32, a first inner side surface 33, a second innerside surface 34, a pressure side inner surface 35, and a suction sideinner surface 36 as shown in FIGS. 2 and 3 . In the illustrativeembodiment, the radially outer top surface 31 is located adjacent thetip 21 and the radially inner bottom surface 22 is located opposite theradially outer top surface 31. As shown in FIG. 2 , the radially innerbottom surface 32 is located slightly radially outward of a halfwaypoint of a radial extent of the airfoil 16. The first inner side surface33 is located adjacent the leading edge 25 of the airfoil 16 and thesecond inner side surface 34 is located opposite the first inner sidesurface 33 and adjacent the trailing edge 27 of the airfoil 16. Thepressure side inner surface 35 is located adjacent the pressure sideexternal surface 24, and the suction side inner surface 36 is locatedopposite the pressure side inner surface 35 and adjacent the suctionside external surface 26.

It should be understood that the cavity 22 may be sized differently inother embodiments such that the surfaces 31, 33, 34, 35, 36 are notlocated directly adjacent the tip 21, the leading and trailing edges 25,27, and the pressure and suction sides 24, 26 of the airfoil 16,respectively. In other words, the cavity 22 may be formed to bevolumetrically larger or smaller than the embodiment illustrated inFIGS. 2 and 3 depending on the expected forces acting on the airfoil 16.

The airfoil body 20 further includes the shear-thickening fluid 30disposed within the cavity 22 as shown in FIGS. 2 and 3 . In theillustrative embodiment, the fluid 30 may be any non-Newtonian fluidthat changes viscosity when force is applied. For example,shear-thickening fluid 30 that may be utilized in the embodimentsdescribed herein may include silica, calcium carbonate, titanium dioxidein ethylene glycol, or polyethylene glycol. The type of shear-thickeningfluid 30 may be selected based on the level of vibration that theairfoil 16 is expected to experience and the amount of damping desiredfor a particular application. In the illustrative embodiments, theshear-thickening fluid 30 is chosen such that the viscosity of the fluidincreases when vibratory forces are applied to the fluid via thestructure of the airfoil 16.

The thicker fluid 30 moves differently than the thinner fluid 30 andthus the vibratory response of the airfoil 16 is altered based on thethicker fluid 30 interacting with the side walls of the cavity 22 andthe at least one obstructing member 28. In this way, vibrations of theairfoil 16 are damped via the movement of the thicker fluid 30 relativeto the side walls of the cavity 22 and the obstructing member 28. Inother embodiments, the fluid 30 may be a fluid that decreases inviscosity in response to experiencing an applied force. This fluid 30will still attenuate vibrations in the airfoil 16 so long as theappropriate frequency is achieved when the fluid's viscosity decreases.

In some embodiments, the airfoil body 20 defines a camber line 60extending from the leading edge 25 to the trailing edge 27 as shown inFIG. 3 . In the illustrative embodiment, the cavity 22 extends beyondthe camber line 60 toward the pressure side inner surface 35 and towardthe suction side inner surface 36. In other embodiments, the cavity 22is sized to not extend beyond the camber line 60 based on the particulardamping application. For example, in scenarios in which more damping isdesired on one side of the camber line 60, the cavity 22 may be formedon that particular side of the camber line 60 within the airfoil 16.

In the illustrative embodiment, the at least one obstructing member 28includes a plurality of pegs 28 that each extend from the pressure sideinner surface 35 to the suction side inner surface 36 of the cavity 22as shown in FIGS. 2 and 3 . The plurality of pegs 28 include multiplerows of pegs 28, each row of pegs 28 extending from the leading edge 25to the trailing edge 27 in a direction generally perpendicular to theleading edge 25 and the trailing edge 27. In the illustrativeembodiment, each row of pegs 28 is spaced apart from adjacent rows ofpegs 28 in a radially direction. In the embodiment shown in FIG. 2 ,each row of pegs 28 includes four or five pegs, and the plurality ofpegs 28 includes eight rows of pegs. Moreover, the rows of pegs 28 arestaggered such that the pegs of a given row are aligned with the spacein between the pegs of an adjacent row. In other embodiments, the numberof pegs, the number of rows of pegs, and the staggering of the pegs maybe adjusted based on the operating condition of the airfoil 16.

In operation, the airfoil 16 may experience an aeromechanic responseand/or vibrations in use, in particular when the airfoil 16 is beingutilized as a blade in a bladed rotor assembly 10 or as a vane in a vaneassembly 70. When the airfoil 16 vibrates, the shear-thickening fluid 30will thicken, or in other words the viscosity of the fluid 30 willincrease. The thicker, higher viscosity fluid 30 moves differently thanthe thinner fluid 30 that existed prior to the vibrations of the airfoil16. Specifically, the thicker fluid 30 does not as easily move past andthrough the obstructing member 28, and thus movement of the fluid 30 isslowed to the desired rate which causes a particular damping effect inthe airfoil 16. Thus, vibrations of the airfoil 16 are damped via themovement of the thicker fluid 30 relative to the side walls of thecavity 22 and the obstructing member 28. Moreover, unsynchronized fluidflow relative to the airfoil 16 mode frequency contributes to additionaldamping.

In the illustrative embodiment, the airfoil 16, which includes theplurality of pegs 28 that extend in a direction from the pressure side24 to the suction side 26, affect a chord-wise motion of the fluid 30.Because of the hindrance of the chord-wise motion of the fluid 30, theplurality of pegs 28 may provide optimal damping of the airfoil 16 inresponse to torsion or twisting of the airfoil 16 in the spanwisedirection. That is, when the airfoil 16 twists along an axis 62 thatextends from the root 23 to the tip 21 of the airfoil 16, the movementof the thickened fluid 30 within the cavity 22 improves the damping ofthe airfoil 16. Moreover, arrangement of the cavity 22 within theairfoil 16 may be altered such that the cavity 22 is located near a peakdisplacement for a particular mode or near a peak strain.

In some embodiments, the cavity 22 is located within the airfoil 16 in alocation that accommodates specific deflection, bending, and/or torsionof the airfoil 16. Specifically, the cavity 22 may be located in an areaof the airfoil 16 in which significant deflection, bending, and/ortorsion is occurring. Embodiments may include cavities arranged in otherareas of the blade, as well be described herein. Each cavity may befurther divided into two or more cavities within the general space zonedby cavity 22. For example, there may be provided a pocket adjacent tothe leading edge, a solid mid-chord area, and an additional pocketadjacent the trailing edge.

In some embodiments, the frequency and vibratory responses of theairfoil 16 as experienced in response to various operating conditions ofthe gas turbine engine 110 may be known prior to manufacturing thecavity 22 such that the location of the cavity 22 may established suchthat a desired damping effect may be achieved based on operatingconditions that the gas turbine engine 110 will experience.

Another embodiment of an airfoil 116 in accordance with the presentdisclosure is shown in FIGS. 4 and 5 . The airfoil 116 is substantiallysimilar to the airfoil 16 shown in FIGS. 2 and 3 and described herein.Accordingly, similar reference numbers in the 100 series indicatefeatures that are common between the airfoil 116 and the airfoil 16. Thedescription of the airfoil 16 is incorporated by reference to apply tothe airfoil 116, except in instances when it conflicts with the specificdescription and the drawings of the airfoil 116. It should be understoodthat the airfoil 116 may be utilized in the gas turbine engine 110similarly to how the airfoil 16 is utilized, in particular in a bladedrotor assembly 10 and/or a vane assembly 70. Moreover, the airfoil 116may be utilized along with the airfoil 16 within a single assembly 10,70, or only airfoils 116 may be utilized. Any combination of theairfoils 16, 116 and the airfoils described in further detail below maybe utilized in the assemblies 10, 70 as well.

The airfoil 116 is formed similarly to the airfoil 16 described above.In particular, the airfoil 116 includes an airfoil body 120 as shown inFIGS. 4 and 5 . The airfoil body 120 includes an airfoil tip 121 spacedapart radially outward from an airfoil root 123, the airfoil root 123located adjacent to the wheel 12, 1212 in embodiments in which theairfoil 116 is utilized in a bladed rotor assembly 10, 1210, as shown inFIG. 17 . In embodiments in which the airfoil 116 is utilized in a vaneassembly 70, 1170, the tip 121 may be located adjacent an outer platform1172 and the root 123 may be located adjacent an inner platform 1174, asshown in FIG. 16 . The airfoil body 120 has a leading edge 125, atrailing edge 127 opposite the leading edge 125, a pressure sideexternal surface 124, and a suction side external surface 126 oppositethe pressure side 124.

The airfoil 116 is formed to include a cavity 122 within the airfoilbody 120 as shown in FIGS. 4 and 5 . The cavity 122 is formed ashollowed-out space similar to the cavity 22, being defined by a radiallyouter top surface 131, a radially inner bottom surface 132, a firstinner side surface 133, a second inner side surface 134, a pressure sideinner surface 135, and a suction side inner surface 136. The cavity 122may be formed to be volumetrically larger or smaller than the embodimentillustrated in FIGS. 4 and 5 depending on the expected forces acting onthe airfoil 116.

The airfoil body 120 further includes a shear-thickening fluid 130disposed within the cavity 122 as shown in FIGS. 4 and 5 . Similar tothe fluid 30 of the airfoil 16, the fluid 130 may be any non-Newtonianfluid that changes viscosity when force is applied, in particularincreasing in thickness such that vibrations of the airfoil 116 aredamped via the movement of the thicker fluid 130 relative to the sidewalls of the cavity 122 and the obstructing member 128. In otherembodiments, the fluid 130 may be a fluid that decreases in viscosity inresponse to experiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 128includes a plurality of radially extending walls 128 as shown in FIGS. 4and 5 . The plurality of radially extending walls 128 includes at leastone first wall 141 that extends radially outwardly away from theradially inner bottom surface 132 towards the radially outer top surface131 of the cavity 122 and at least one second wall 142 that extendsradially inwardly away from the radially outer top surface 131 towardsthe radially inner bottom surface 132 of the cavity 122. The at leastone first wall 141 extends partway from the radially inner bottomsurface 132 towards the radially outer top surface 131 and the at leastone second wall extends partway from the radially outer top surface 131towards the radially inner bottom surface 132. The walls 141, 142 have awidth that extends from the pressure side inner surface 135 to thesuction side inner surface 136 as shown in FIG. 5 . In the embodimentshown in FIG. 4 , the plurality of walls 128 alternate between firstwalls 141 and second walls 142, and include four first walls 141 andfour second walls 142.

In the illustrative embodiment, the first walls 141 extend generallyperpendicularly away from the radially inner bottom surface 132 and thesecond walls 142 extend generally perpendicularly away from the radiallyouter top surface 131 as shown in FIG. 4 . Each wall 141, 142 includes aterminal end 143, 144. In the illustrative embodiment, each first wall141 extends radially beyond the terminal end 144 of an adjacent secondwall 142, and each second wall 142 extends radially beyond the terminalend 143 of an adjacent first wall 141. In other embodiments, the numberof walls and the extent of each wall may be adjusted based on theoperating condition of the airfoil 116. Similar to the obstructingmember 28 described above, the plurality of walls 128 are configured toobstruct movement of the thickened fluid 30 in order to dampenvibrations of the airfoil 116.

Another embodiment of an airfoil 216 in accordance with the presentdisclosure is shown in FIG. 6 . The airfoil 216 is substantially similarto the airfoils 16, 116 described herein. Accordingly, similar referencenumbers in the 200 series indicate features that are common between theairfoil 216 and the airfoils 16, 116. The descriptions of the airfoils16, 116 are incorporated by reference to apply to the airfoil 216,except in instances when it conflicts with the specific description andthe drawings of the airfoil 216. It should be understood that theairfoil 216 may be utilized in the gas turbine engine 110 similarly tohow the airfoils 16, 116 are utilized, in particular in a bladed rotorassembly 10 and/or a vane assembly 70. Moreover, the airfoil 216 may beutilized along with the airfoils 16, 116 within a single assembly 10,70, or only airfoils 216 may be utilized. Any combination of theairfoils 16, 116, 216 and the airfoils described in further detail belowmay be utilized in the assemblies 10, 70 as well.

The airfoil 216 is formed similarly to the airfoil 16 described above.In particular, the airfoil 216 includes an airfoil body 220 as shown inFIG. 6 . The airfoil body 220 includes an airfoil tip 221 spaced apartradially outward from an airfoil root 223, the airfoil root 223 locatedadjacent to the wheel 12 in embodiments in which the airfoil 216 isutilized in a bladed rotor assembly 10, as shown in FIG. 17 . Inembodiments in which the airfoil 216 is utilized in a vane assembly 70,the tip 221 may be located adjacent an outer platform 1172 and the root223 may be located adjacent an inner platform 1174, as shown in FIG. 16. The airfoil body 220 has a leading edge 225, a trailing edge 227opposite the leading edge 225, a pressure side external surface 224, anda suction side external surface 226 opposite the pressure side 224.

The airfoil 216 is formed to include a cavity 222 within the airfoilbody 220 as shown in FIG. 6 . The cavity 222 is formed as hollowed-outspace similar to the cavity 22, 122, being defined by a radially outertop surface 231, a radially inner bottom surface 232, a first inner sidesurface 233, a second inner side surface 234, a pressure side innersurface 235, and a suction side inner surface 236. The cavity 222 may beformed to be volumetrically larger or smaller than the embodimentillustrated in FIG. 6 depending on the expected forces acting on theairfoil 216.

The airfoil body 220 further includes a shear-thickening fluid 230disposed within the cavity 222 as shown in FIG. 6 . Similar to the fluid30, 130 of the airfoils 16, 116, the fluid 230 may be any non-Newtonianfluid that changes viscosity when force is applied, in particularincreasing in thickness such that vibrations of the airfoil 216 aredamped via the movement of the thicker fluid 230 relative to the sidewalls of the cavity 222 and the obstructing member 228. In otherembodiments, the fluid 230 may be a fluid that decreases in viscosity inresponse to experiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 228includes a plurality of angled walls 228 as shown in FIG. 6 . Theplurality of angled walls 228 include at least one first angled wall 241that extends away from the first inner side surface 233 towards theradially inner bottom surface 232 and the second inner side surface 234,and at least one second angled wall 242 that extends away from thesecond inner side surface 234 towards the radially outer top surface 231and the first inner side surface 233. The at least one first angled wall241 extends at a first angle relative to the first inner side surface233 and extends partway from the first inner side surface 233 towardsthe radially inner bottom surface 232 and the second inner side surface234. Similarly, the at least one second angled wall 242 extends at thefirst angle 245 relative to the first inner side surface 233 and extendspartway from the second inner side surface 234 towards the radiallyouter top surface 231 and the first inner side surface 233. In theillustrative embodiment, each first angled wall 241 is parallel to eachsecond angled wall 242.

In the illustrative embodiment, the plurality of walls 228 includes fourfirst angled walls 241 and four second angled walls 242. Each angledwall 241, 242 includes a terminal end 243, 244. The plurality of angledwalls 228 alternate between the first angled walls 241 and the secondangled walls 242 in a direction from the radially inner bottom surface232 to the radially outer top surface 231. In the illustrativeembodiment, each first angled wall 241 extends beyond the terminal end244 of an adjacent second angled wall 242, and each second angled wall242 extends radially beyond the terminal end 243 of an adjacent firstangled wall 241. In other embodiments, the number of walls and theextent of each wall may be adjusted based on the operating condition ofthe airfoil 216. Similar to the obstructing member 28, 128 describedabove, the plurality of walls 228 are configured to obstruct movement ofthe thickened fluid 230 in order to dampen vibrations of the airfoil216.

Another embodiment of an airfoil 316 in accordance with the presentdisclosure is shown in FIGS. 7 and 8 . The airfoil 316 is substantiallysimilar to the airfoils 16, 116, 216 described herein. Accordingly,similar reference numbers in the 300 series indicate features that arecommon between the airfoil 316 and the airfoils 16, 116, 216. Thedescriptions of the airfoils 16, 116, 216 are incorporated by referenceto apply to the airfoil 316, except in instances when it conflicts withthe specific description and the drawings of the airfoil 316. It shouldbe understood that the airfoil 316 may be utilized in the gas turbineengine 110 similarly to how the airfoils 16, 116, 216 are utilized, inparticular in a bladed rotor assembly 10 and/or a vane assembly 70.Moreover, the airfoil 316 may be utilized along with the airfoils 16,116, 216 within a single assembly 10, 70, or only airfoils 316 may beutilized. Any combination of the airfoils 16, 116, 216, 316 and theairfoils described in further detail below may be utilized in theassemblies 10, 70 as well.

The airfoil 316 is formed similarly to the airfoils 16, 116, 216described above. In particular, the airfoil 316 includes an airfoil body320 as shown in FIG. 7 . The airfoil body 320 includes an airfoil tip321 spaced apart radially outward from an airfoil root 323, the airfoilroot 323 located adjacent to the wheel 12 in embodiments in which theairfoil 316 is utilized in a bladed rotor assembly 10, as shown in FIG.17 . In embodiments in which the airfoil 316 is utilized in a vaneassembly 70, the tip 321 may be located adjacent an outer platform 1172and the root 323 may be located adjacent an inner platform 1174, asshown in FIG. 16 . The airfoil body 320 has a leading edge 325, atrailing edge 327 opposite the leading edge 325, a pressure sideexternal surface 324, and a suction side external surface 326 oppositethe pressure side 324.

The airfoil 316 is formed to include a cavity 322 within the airfoilbody 320 as shown in FIGS. 7 and 8 . The cavity 322 is formed ashollowed-out space similar to the cavity 22, 122, 222 being defined by aradially outer top surface 331, a radially inner bottom surface 332, afirst inner side surface 333, a second inner side surface 334, apressure side inner surface 335, and a suction side inner surface 336.The cavity 322 may be formed to be volumetrically larger or smaller thanthe embodiment illustrated in FIGS. 7 and 8 depending on the expectedforces acting on the airfoil 316. In an alternative embodiment, the meshgrid 328 may include perforated sheet metal having holes positionedsimilarly to the mesh described above, or may include a sheet metalincluding holes therethrough and having ridges or other similar featuresthat extend away from the sheet and abut at least one of the pressureand suction side surfaces. In further embodiments, the mesh grid 328 mayinclude a 3D-printed sheet including the features described—above.

The airfoil body 320 further includes a shear-thickening fluid 330disposed within the cavity 322 as shown in FIGS. 7 and 8 . Similar tothe fluid 30, 130 of the airfoils 16, 116, 216, the fluid 330 may be anynon-Newtonian fluid that changes viscosity when force is applied, inparticular increasing in thickness such that vibrations of the airfoil316 are damped via the movement of the thicker fluid 330 relative to theside walls of the cavity 322 and the obstructing member 328. In otherembodiments, the fluid 330 may be a fluid that decreases in viscosity inresponse to experiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 328includes a mesh grid 328 as shown in FIGS. 7 and 8 . The mesh grid isformed by a first plurality of thin rods 341 extending from the firstinner side surface 333 to the second inner side surface 334, and asecond plurality of thin rods 342 extending from the radially innerbottom surface 332 to the radially outer top surface 331. In otherembodiments, the mesh grid 328 may include thin wires as opposed torods. Although the view of FIG. 8 shows the fluid 330 over the rods 341,it should be understood that the rods 341 are solid and this is onlyshown for clarity purposes.

As can be seen in FIG. 8 , the mesh grid suction side 344 is spacedapart from the suction side inner surface 336 of the cavity 322 and themesh grid pressure side 345 is spaced apart from the pressure side innersurface 335 of the cavity 322. In this way, the mesh grid 328 is formedas a mesh panel that extends from the first inner side surface 333 tothe second inner side surface 334. In other embodiments, the number ofrods, the extent of each rod, and the width of the mesh grid relative tothe pressure and suction side surfaces may be adjusted based on theoperating condition of the airfoil 316. Similar to the obstructingmember 28, 128, 228 described above, the mesh grid 328 is configured toobstruct movement of the thickened fluid 330 in order to dampenvibrations of the airfoil 316. Although the view of FIG. 8 shows thefluid 330 over the rods 341, it should be understood that the rods 341are solid and this is only shown for clarity purposes.

In the illustrative embodiment, the airfoil 316, which includes the meshgrid 316, affects a through-thickness motion of the fluid 330. Becauseof the hindrance of the through-thickness motion of the fluid 330, themesh grid 330 may provide optimal damping of the airfoil 316 in responseto bending of the airfoil 16. That is, when the airfoil 16 bends alongan axis 362 that extends from the leading edge 325 to the trailing edge327 of the airfoil 316, the movement of the thickened fluid 330 withinthe cavity 322 improves the damping of the airfoil 316. Moreover,arrangement of the cavity 322 within the airfoil 316 may be altered suchthat the cavity 322 is located near a peak displacement for a particularmode or near a peak strain.

Another embodiment of an airfoil 416 in accordance with the presentdisclosure is shown in FIG. 9 . The airfoil 416 is substantially similarto the airfoils 16, 116, 216, 316 described herein. Accordingly, similarreference numbers in the 400 series indicate features that are commonbetween the airfoil 416 and the airfoils 16, 116, 216, 316. Thedescriptions of the airfoils 16, 116, 216, 316 are incorporated byreference to apply to the airfoil 416, except in instances when itconflicts with the specific description and the drawings of the airfoil416. It should be understood that the airfoil 416 may be utilized in thegas turbine engine 110 similarly to how the airfoils 16, 116, 216, 316are utilized, in particular in a bladed rotor assembly 10 and/or a vaneassembly 70. Moreover, the airfoil 416 may be utilized along with theairfoils 16, 116, 216, 316 within a single assembly 10, 70, or onlyairfoils 416 may be utilized. Any combination of the airfoils 16, 116,216, 316, 416 and the airfoils described in further detail below may beutilized in the assemblies 10, 70 as well.

The airfoil 416 is formed similarly to the airfoils 16, 116, 216, 316described above. In particular, the airfoil 416 includes an airfoil body420 as shown in FIG. 9 . The airfoil body 420 includes an airfoil tip421 spaced apart radially outward from an airfoil root 423, the airfoilroot 423 located adjacent to the wheel 12 in embodiments in which theairfoil 416 is utilized in a bladed rotor assembly 10, as shown in FIG.17 . In embodiments in which the airfoil 416 is utilized in a vaneassembly 70, the tip 421 may be located adjacent an outer platform 1172and the root 423 may be located adjacent an inner platform 1174, asshown in FIG. 16 . The airfoil body 420 has a leading edge 425, atrailing edge 427 opposite the leading edge 425, a pressure sideexternal surface 424, and a suction side external surface 426 oppositethe pressure side 424.

The airfoil 416 is formed to include a cavity 422 within the airfoilbody 420 as shown in FIG. 9 . The cavity 422 is formed as hollowed-outspace similar to the cavity 22, 122, being defined by a radially outertop surface 431, a radially inner bottom surface 432, a first inner sidesurface 433, a second inner side surface 434, a pressure side innersurface 435, and a suction side inner surface 436. The cavity 422 may beformed to be volumetrically larger or smaller than the embodimentillustrated in FIG. 9 depending on the expected forces acting on theairfoil 416.

The airfoil body 420 further includes a shear-thickening fluid 430disposed within the cavity 422 as shown in FIG. 9 . Similar to the fluid30, 130, 230, 330 of the airfoils 16, 116, 216, 316, the fluid 430 maybe any non-Newtonian fluid that changes viscosity when force is applied,in particular increasing in thickness such that vibrations of theairfoil 416 are damped via the movement of the thicker fluid 430relative to the side walls of the cavity 422 and the obstructing member428. In other embodiments, the fluid 430 may be a fluid that decreasesin viscosity in response to experiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 428includes a plurality of angled walls 428 as shown in FIG. 9 . The angledwalls 428 are formed similarly to the angled walls 228 described above,in particular the arrangement of the first angled walls 441 and thesecond angled walls 442, and the walls 441, 442 alternating andextending beyond the terminal ends 443, 444 of the adjacent walls 441,442. The plurality of angled walls 428 differ from the angled walls 228in that the radially inner bottom surface 432 of the cavity 422 islocated radially inwardly of a halfway point of a radial extent of theairfoil body 420 as shown in FIG. 9 . As such, the cavity 422 occupies amajority of the interior of the airfoil body 420. In the embodimentshown in FIG. 9 , the plurality of angled walls 428 includes five firstangled walls 441 and six second angled walls 442.

In other embodiments, the number of walls and the extent of each wallmay be adjusted based on the operating condition of the airfoil 416.Similar to the obstructing member 28, 128, 228, 328 described above, theplurality of walls 428 are configured to obstruct movement of thethickened fluid 430 in order to dampen vibrations of the airfoil 416.

Another embodiment of an airfoil 516 in accordance with the presentdisclosure is shown in FIG. 10 . The airfoil 516 is substantiallysimilar to the airfoils 16, 116, 216, 316, 416 described herein.Accordingly, similar reference numbers in the 500 series indicatefeatures that are common between the airfoil 516 and the airfoils 16,116, 216, 316, 416. The descriptions of the airfoils 16, 116, 216, 316,416 are incorporated by reference to apply to the airfoil 516, except ininstances when it conflicts with the specific description and thedrawings of the airfoil 516. It should be understood that the airfoil516 may be utilized in the gas turbine engine 110 similarly to how theairfoils 16, 116, 216, 316, 416 are utilized, in particular in a bladedrotor assembly 10 and/or a vane assembly 70. Moreover, the airfoil 516may be utilized along with the airfoils 16, 116, 216, 316, 416 within asingle assembly 10, 70, or only airfoils 516 may be utilized. Anycombination of the airfoils 16, 116, 216, 316, 416, 516 and the airfoilsdescribed in further detail below may be utilized in the assemblies 10,70 as well.

The airfoil 516 is formed similarly to the airfoils 16, 116, 216, 316,416 described above. In particular, the airfoil 516 includes an airfoilbody 520 as shown in FIG. 10 . The airfoil body 520 includes an airfoiltip 521 spaced apart radially outward from an airfoil root 523, theairfoil root 523 located adjacent to the wheel 12 in embodiments inwhich the airfoil 516 is utilized in a bladed rotor assembly 10, asshown in FIG. 17 . In embodiments in which the airfoil 516 is utilizedin a vane assembly 70, the tip 521 may be located adjacent an outerplatform 1172 and the root 523 may be located adjacent an inner platform1174, as shown in FIG. 16 . The airfoil body 520 has a leading edge 525,a trailing edge 527 opposite the leading edge 525, a pressure sideexternal surface 524, and a suction side external surface 526 oppositethe pressure side 524.

The airfoil 516 is formed to include a cavity 522 within the airfoilbody 520 as shown in FIG. 10 . The cavity 522 is formed as hollowed-outspace similar to the cavity 22, 122, 222, 322, 422 being defined by aradially outer top surface 531, a radially inner bottom surface 532, afirst inner side surface 533, a second inner side surface 534, apressure side inner surface 535, and a suction side inner surface 536.The cavity 522 may be formed to be volumetrically larger or smaller thanthe embodiment illustrated in FIG. 10 depending on the expected forcesacting on the airfoil 516.

The airfoil body 520 further includes a shear-thickening fluid 530disposed within the cavity 522 as shown in FIG. 10 . Similar to thefluid 30, 130, 230, 330, 430 of the airfoils 16, 116, 216, 316, 416, thefluid 530 may be any non-Newtonian fluid that changes viscosity whenforce is applied, in particular increasing in thickness such thatvibrations of the airfoil 516 are damped via the movement of the thickerfluid 530 relative to the side walls of the cavity 522 and theobstructing member 528. In other embodiments, the fluid 530 may be afluid that decreases in viscosity in response to experiencing an appliedforce.

In the illustrative embodiment, the at least one obstructing member 528includes a plurality of walls 528 as shown in FIG. 10 . The plurality ofwalls 528 are formed similarly to the walls 128 described above, inparticular the first and second walls 541, 542 alternating and extendingbeyond the terminal ends 543, 544 of the adjacent walls 541, 542. Theplurality of walls 528 differ from the walls 128 in that the first walls541 extend generally perpendicularly away from the first inner sidesurface 533 of the cavity 522 and the second walls 542 extend generallyperpendicularly away from the second inner side surface 534 of the firstcavity 522. In the illustrative embodiment, the walls 528 include fourfirst walls 541 and four second walls 542.

In other embodiments, the number of walls and the extent of each wallmay be adjusted based on the operating condition of the airfoil 516.Similar to the obstructing members 28, 128, 228, 328, 428 describedabove, the plurality of walls 528 are configured to obstruct movement ofthe thickened fluid 530 in order to dampen vibrations of the airfoil516.

Another embodiment of an airfoil 616 in accordance with the presentdisclosure is shown in FIG. 11 . The airfoil 616 is substantiallysimilar to the airfoils 16, 116, 216, 316, 416, 516 described herein.Accordingly, similar reference numbers in the 600 series indicatefeatures that are common between the airfoil 616 and the airfoils 16,116, 216, 316, 416, 516. The descriptions of the airfoils 16, 116, 216,316, 416, 516 are incorporated by reference to apply to the airfoil 616,except in instances when it conflicts with the specific description andthe drawings of the airfoil 616. It should be understood that theairfoil 616 may be utilized in the gas turbine engine 110 similarly tohow the airfoils 16, 116, 216, 316, 416, 516 are utilized, in particularin a bladed rotor assembly 10 and/or a vane assembly 70. Moreover, theairfoil 616 may be utilized along with the airfoils 16, 116, 216, 316,416, 516 within a single assembly 10, 70, or only airfoils 616 may beutilized. Any combination of the airfoils 16, 116, 216, 316, 416, 516,616 and the airfoils described in further detail below may be utilizedin the assemblies 10, 70 as well.

The airfoil 616 is formed similarly to the airfoils 16, 116, 216, 316,416, 516 described above. In particular, the airfoil 616 includes anairfoil body 620 as shown in FIG. 11 . Like the airfoils 16, 116, 216,316, 416, 516, the airfoil body 620 includes an airfoil tip (notillustrated due to cross-section) spaced apart radially outward from anairfoil root 623, a leading edge 625, a trailing edge 627 opposite theleading edge 625, a pressure side external surface 624, and a suctionside external surface 626 opposite the pressure side 624.

The airfoil 616 is formed to include a cavity 622 within the airfoilbody 620 as shown in FIG. 11 . The cavity 622 is formed as hollowed-outspace similar to the cavity 22, 122, 222, 322, 422, 522 being defined bya radially outer top surface (not illustrated due to cross-section), aradially inner bottom surface (not illustrated due to cross-section), afirst inner side surface 633, a second inner side surface 634, apressure side inner surface 635, and a suction side inner surface 636.The cavity 622 may be formed to be volumetrically larger or smaller thanthe embodiment illustrated in FIG. 11 depending on the expected forcesacting on the airfoil 616.

The airfoil body 620 further includes a shear-thickening fluid 630disposed within the cavity 622 as shown in FIG. 11 . Similar to thefluid 30, 130, 230, 330, 430, 530 of the airfoils 16, 116, 216, 316,416, 516, the fluid 630 may be any non-Newtonian fluid that changesviscosity when force is applied, in particular increasing in thicknesssuch that vibrations of the airfoil 616 are damped via the movement ofthe thicker fluid 630 relative to the side walls of the cavity 622 andthe obstructing member 628. In other embodiments, the fluid 630 may be afluid that decreases in viscosity in response to experiencing an appliedforce.

In the illustrative embodiment, the at least one obstructing member 628includes a plurality of ridges 628 as shown in FIG. 11 . The pluralityof ridges include at least one first ridge 641 extending away from thepressure side inner surface 635 of the cavity 622 and at least onesecond ridge 642 extending away from the suction side inner surface 636of the cavity 622. Each first ridge 641 and each second ridge 642includes a terminal end 643, 644. The plurality of ridges 628 alternatebetween the at least one first ridge 641 and the at least one secondridge 642 in a direction from the leading edge 625 to the trailing edge627 of the airfoil body 620. Each first ridge 641 extends beyond theterminal end 644 of an adjacent second ridge 642 in a direction from thepressure side inner surface 635 to the suction side inner surface 636,and each second ridge 642 extends beyond the terminal end 643 of anadjacent second ridge 641.

In the illustrative embodiment, the longitudinal extent of the ridges628 extend in a direction from the root 623 to the tip of the airfoilbody 620. the ridges 628 are formed to have cross-sectional trapezoidalshapes. In other embodiments, the other shapes may be utilized as theshapes of the ridges 628, such as triangles, squares, semi-circles, andother similar shapes, so long as the ridges 628 alter the movement ofthe thickened fluid 630. The plurality of ridges 628 may include fivetotal ridges 628 as shown in FIG. 11 . In other embodiments, the numberof ridges, the extent of the ridges, and the altering of the ridges maybe adjusted based on the operating condition of the airfoil 616. Similarto the obstructing members 28, 128, 228, 328, 428, 528 described above,the ridges 628 is configured to obstruct movement of the thickened fluid630 in order to dampen vibrations of the airfoil 616.

Another embodiment of an airfoil 716 in accordance with the presentdisclosure is shown in FIG. 12 . The airfoil 716 is substantiallysimilar to the airfoils 16, 116, 216, 316, 416, 516, 616 describedherein. Accordingly, similar reference numbers in the 700 seriesindicate features that are common between the airfoil 716 and theairfoils 16, 116, 216, 316, 416, 516, 616. The descriptions of theairfoils 16, 116, 216, 316, 416, 516, 616 are incorporated by referenceto apply to the airfoil 716, except in instances when it conflicts withthe specific description and the drawings of the airfoil 716. It shouldbe understood that the airfoil 716 may be utilized in the gas turbineengine 110 similarly to how the airfoils 16, 116, 216, 316, 416, 516,616 are utilized, in particular in a bladed rotor assembly 10 and/or avane assembly 70. Moreover, the airfoil 716 may be utilized along withthe airfoils 16, 116, 216, 316, 416, 516, 616 within a single assembly10, 70, or only airfoils 716 may be utilized. Any combination of theairfoils 16, 116, 216, 316, 416, 516, 616, 716 and the airfoilsdescribed in further detail below may be utilized in the assemblies 10,70 as well.

The airfoil 716 is formed similarly to the airfoils 16, 116, 216, 316,416, 516, 616 described above. In particular, the airfoil 716 includesan airfoil body 720 as shown in FIG. 12 . Like the airfoils 16, 116,216, 316, 416, 516, the airfoil body 720 includes an airfoil tip (notillustrated due to cross-section) spaced apart radially outward from anairfoil root 723, a leading edge 725, a trailing edge 727 opposite theleading edge 725, a pressure side external surface 724, and a suctionside external surface 726 opposite the pressure side 724.

The airfoil 716 is formed to include a cavity 722 within the airfoilbody 720 as shown in FIG. 12 . The cavity 722 is formed as hollowed-outspace similar to the cavity 22, 122, 222, 322, 422, 522, 622 beingdefined by a radially outer top surface (not illustrated due tocross-section), a radially inner bottom surface (not illustrated due tocross-section), a first inner side surface 733, a second inner sidesurface 734, a pressure side inner surface 735, and a suction side innersurface 736. The cavity 722 may be formed to be volumetrically larger orsmaller than the embodiment illustrated in FIG. 12 depending on theexpected forces acting on the airfoil 716.

The airfoil body 720 further includes a shear-thickening fluid 730disposed within the cavity 722 as shown in FIG. 12 . Similar to thefluid 30, 130, 230, 330, 430, 530, 630 of the airfoils 16, 116, 216,316, 416, 516, 616 the fluid 730 may be any non-Newtonian fluid thatchanges viscosity when force is applied, in particular increasing inthickness such that vibrations of the airfoil 716 are damped via themovement of the thicker fluid 730 relative to the side walls of thecavity 722 and the obstructing member 728. In other embodiments, thefluid 730 may be a fluid that decreases in viscosity in response toexperiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 728includes a plurality of walls 728 as shown in FIG. 12 . The plurality ofwalls include at least one first wall 741 extending from the pressureside inner surface 735 to the suction side inner surface 736 at a firstangle and at least one second wall 742 extending from the pressure sideinner surface 735 to the suction side inner surface 736 at a secondangle. The plurality of walls 728 alternate between the at least onefirst wall 741 and the at least one second wall 742 in a direction fromthe leading edge 724 to the trailing edge 727 of the airfoil body 720.Each wall 741, 742 includes an opening 743 formed therein to allow fluid730 to pass therethrough and throughout the cavity 722. In theillustrative embodiment, the openings 743 are offset with the openings743 in adjacent walls 741, 742 as shown in FIG. 12 .

In other embodiments, the number of walls, the extent of the walls, thealtering of the walls, and the placement of the openings may be adjustedbased on the operating condition of the airfoil 716. Similar to theobstructing members 28, 128, 228, 328, 428, 528, 628 described above,the mesh grid 728 is configured to obstruct movement of the thickenedfluid 730 in order to dampen vibrations of the airfoil 716.

Further embodiments of airfoils 816, 916 in accordance with the presentdisclosure is shown in FIGS. 13 and 14 . The airfoils 816, 916 aresubstantially similar to the airfoils 16, 116, 216, 316, 416, 516, 616,716 described herein. Accordingly, similar reference numbers in the 800and 900 series indicate features that are common between the airfoils816, 916 and the airfoils 16, 116, 216, 316, 416, 516, 616, 716. Thedescriptions of the airfoils 16, 116, 216, 316, 416, 516, 616, 716 areincorporated by reference to apply to the airfoils 816, 916 except ininstances when it conflicts with the specific description and thedrawings of the airfoils 816, 916. It should be understood that theairfoils 816, 916 may be utilized in the gas turbine engine 110similarly to how the airfoils 16, 116, 216, 316, 416, 516, 616, 716 areutilized, in particular in a bladed rotor assembly 10 and/or a vaneassembly 70. Moreover, the airfoils 816, 916 may be utilized along withthe airfoils 16, 116, 216, 316, 416, 516, 616, 716 within a singleassembly 10, 70, or only airfoils 816, 916 may be utilized. Anycombination of the airfoils 16, 116, 216, 316, 416, 516, 616, 716 andthe airfoils described in further detail below may be utilized in theassemblies 10, 70 as well.

The airfoils 816, 916 are formed similarly to the airfoils 16, 116, 216,316, 416, 516, 616, 716 described above. In particular, the airfoil 716includes an airfoil body 820, 920 as shown in FIGS. 13 and 14 . Like theairfoils 16, 116, 216, 316, 416, 516, 616, 716, the airfoil body 820,920 includes an airfoil tip (not illustrated due to cross-section)spaced apart radially outward from an airfoil root 823, 923, a leadingedge 825, 925, a trailing edge 827, 927 opposite the leading edge 825,925, a pressure side external surface 824, 924, and a suction sideexternal surface 826, 926 opposite the pressure side 824, 924.

The airfoils 816, 916 are formed to include a cavity 822, 922 within theairfoil body 820, 920 as shown in FIGS. 13 and 14 . The cavity 822, 922is formed as hollowed-out space similar to the cavity 22, 122, 222, 322,422, 522, 622, 722 being defined by a radially outer top surface (notillustrated due to cross-section), a radially inner bottom surface (notillustrated due to cross-section), a first inner side surface 833, 933,a second inner side surface 834, 934, a pressure side inner surface 835,935, and a suction side inner surface 836, 936. The cavity 822, 922 maybe formed to be volumetrically larger or smaller than the embodimentillustrated in FIGS. 13 and 14 depending on the expected forces actingon the airfoil 816, 916.

The airfoil body 820, 920 further includes a shear-thickening fluid 830,930 disposed within the cavity 822, 922 as shown in FIGS. 13 and 14 .Similar to the fluid 30, 130, 230, 330, 430, 530, 630, 730 of theairfoils 16, 116, 216, 316, 416, 516, 616, 716, the fluid 830, 930 maybe any non-Newtonian fluid that changes viscosity when force is applied,in particular increasing in thickness such that vibrations of theairfoil 816, 916 are damped via the movement of the thicker fluid 830,930 relative to the side walls of the cavity 822, 922 and theobstructing member 828, 928. In other embodiments, the fluid 830, 930may be a fluid that decreases in viscosity in response to experiencingan applied force.

In the illustrative embodiment, the at least one obstructing member 828,928 includes a mesh grid 828, 928 as shown in FIGS. 13 and 14 . The meshgrids 828, 928 are formed similarly to the mesh grid 328 describedabove. In the embodiment shown in FIG. 13 , the mesh grid 828 includes afirst plurality of thin rods 841 extending from the first inner sidesurface 833 to the second inner side surface 834 and a second pluralityof thin rods 842 extending from the radially inner bottom surface to theradially outer top surface (not illustrated due to cross-section). Inthe embodiment shown in FIG. 14 , the mesh grid 928 includes a firstplurality of thin rods 941 extending from the pressure side innersurface 935 to the suction side inner surface 936 and a second pluralityof thin rods 942 extending from the radially inner bottom surface to theradially outer top surface (not illustrated due to cross-section).Although the views of FIGS. 13 and 14 show the fluid 830, 930 over therods, it should be understood that the rods are solid and this is onlyshown for clarity purposes.

The mesh grid 828 of FIG. 13 differs from the mesh grid 328 in that themesh grid 328 is curved in a direction from the leading edge 825 to thetrailing edge 827. The mesh grid 928 of FIG. 14 differs from the meshgrid 328 in that the mesh grid 928 includes a plurality of mesh gridpanels 950 that each extend from the pressure side inner surface 935 tothe suction side inner surface 936. In other embodiments, the number ofrods, the extent of each rod, and the width of the mesh grids relativeto the pressure and suction side surfaces may be adjusted based on theoperating condition of the airfoil 816, 916. Similar to the obstructingmember 28, 128, 228, 328, 428, 528, 628, 728 described above, the meshgrids 828, 928 are configured to obstruct movement of the thickenedfluid 830, 930 in order to dampen vibrations of the airfoil 816, 916.

Another embodiment of an airfoil 1016 in accordance with the presentdisclosure is shown in FIG. 15 . The airfoil 1016 is substantiallysimilar to the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916described herein. Accordingly, similar reference numbers in the 1000series indicate features that are common between the airfoil 1016 andthe airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916. Thedescriptions of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816,916 are incorporated by reference to apply to the airfoil 1016, exceptin instances when it conflicts with the specific description and thedrawings of the airfoil 1016. It should be understood that the airfoil1016 may be utilized in the gas turbine engine 110 similarly to how theairfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916 are utilized,in particular in a bladed rotor assembly 10 and/or a vane assembly 70.Moreover, the airfoil 1016 may be utilized along with the airfoils 16,116, 216, 316, 416, 516, 616, 716, 816, 916 within a single assembly 10,70, or only airfoils 1016 may be utilized. Any combination of theairfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916, 1016 and theairfoils described in further detail below may be utilized in theassemblies 10, 70 as well.

The airfoil 1016 is formed similarly to the airfoils 16, 116, 216, 316,416, 516, 616, 716, 816, 916 described above. In particular, the airfoil1016 includes an airfoil body 1020 as shown in FIG. 15 . Like theairfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916, the airfoilbody 1020 includes an airfoil tip 1021 spaced apart radially outwardfrom an airfoil root 1023, a leading edge and a trailing edge oppositethe leading edge (both not illustrated due to cross-section), a pressureside external surface 1024, and a suction side external surface 1026opposite the pressure side 1024.

The airfoil 1016 is formed to include a cavity 1022 within the airfoilbody 1020 as shown in FIG. 11 . The cavity 1022 is formed ashollowed-out space similar to the cavity 22, 122, 222, 322, 422, 522,622, 722, 822, 922 being defined by a radially outer top surface 1031, aradially inner bottom surface 1032, a first inner side surface and asecond inner side surface (both not illustrated due to cross-section), apressure side inner surface 1035, and a suction side inner surface 1036.The cavity 1022 may be formed to be volumetrically larger or smallerthan the embodiment illustrated in FIG. 15 depending on the expectedforces acting on the airfoil 1016.

The airfoil body 1020 further includes a shear-thickening fluid 1030disposed within the cavity 1022 as shown in FIG. 15 . Similar to thefluid 30, 130, 230, 330, 430, 530, 630, 730, 830, 930 of the airfoils16, 116, 216, 316, 416, 516, 616, 716, 816, 916, the fluid 1030 may beany non-Newtonian fluid that changes viscosity when force is applied, inparticular increasing in thickness such that vibrations of the airfoil1016 are damped via the movement of the thicker fluid 1030 relative tothe side walls of the cavity 1022 and the obstructing member 1028. Inother embodiments, the fluid 1030 may be a fluid that decreases inviscosity in response to experiencing an applied force.

In the illustrative embodiment, the at least one obstructing member 1028includes a plurality of ridges 1028 as shown in FIG. 15 . The pluralityof ridges 1028 are formed similarly to the ridges 628 described above,in particular to include at least one first ridge 1041 extending awayfrom the pressure side inner surface 1035 and at least one second ridge1042 extending away from the suction side inner surface 1036. Each firstridge 1041 and each second ridge 1042 includes a terminal end 1043,1044. The plurality of ridges 1028 alternate between the at least onefirst ridge 1041 and the at least one second ridge 1042 in a directionfrom the radially inner bottom surface 1032 to the radially outer topsurface 1031. Each first ridge 1041 extends beyond the terminal end 1044of an adjacent second ridge 1042 in the direction from the radiallyinner bottom surface 1032 to the radially outer top surface 1031, andeach second ridge 1042 extends beyond the terminal end 1043 of anadjacent second ridge 1041.

The ridges 1028 differ from the ridges 628 described above in that thelongitudinal extent of the ridges 1028 extend in a direction from theleading edge to the trailing edge of the airfoil body 1020 as shown inFIG. 15 . In the illustrative embodiment, the ridges 1028 are formed tohave cross-sectional trapezoidal shapes. In other embodiments, the othershapes may be utilized as the shapes of the ridges 1028, such astriangles, squares, semi-circles, and other similar shapes, so long asthe ridges 1028 alter the movement of the thickened fluid 1030. Theplurality of ridges 1028 may include five total ridges 1028 as shown inFIG. 15 . In other embodiments, the number of ridges, the extent of theridges, and the altering of the ridges may be adjusted based on theoperating condition of the airfoil 1016. Similar to the obstructingmembers 28, 128, 228, 328, 428, 528, 628, 728, 828, 928 described above,the ridges 1028 is configured to obstruct movement of the thickenedfluid 1030 in order to dampen vibrations of the airfoil 1016.

FIG. 16 illustrates an exemplary vane assembly 70, 1170 that may utilizeany of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916,1016 described above. The vane assembly 70, 1170 may include an outerplatform 1172, and inner platform 1174, and a plurality of airfoils 1116formed as vanes of the vane assembly 70, 1170. In response to the vaneassembly 70, 1170 as a whole or individual airfoils 1116 experiencing anaeromechanic response and/or vibrations during use, the shear-thickeningfluid 30, 130, 230, 330, 430, 530, 630, 730, 830, 930, 1030 willincrease in viscosity and thus the airfoil vibrations will be damped. Inthe illustrative embodiment, the vane assembly 70, 1170 is utilized asan outlet guide vane assembly at a fan exit 116 of the gas turbineengine 110.

FIG. 17 illustrates an exemplary bladed rotor assembly 10, 1210 that mayutilize any of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816,916, 1016 described above. The bladed rotor assembly 10, 1210 mayinclude an inner wheel 1212 configured to rotate around the central axis11 of the gas turbine engine 110. The plurality of airfoils 16, 116,216, 316, 416, 516, 616, 716, 816, 916, 1016 are formed as blades of thebladed rotor assembly 10, 1210 that extend radially outwardly from thewheel 1212. The blades may attach to the wheel 1212 via the root 1223 ofthe blade, and each blade may also have a blade tip 1221. In the exampleillustrated in FIG. 17 , the blade may include a cavity 1222, aplurality of pegs 1228 similar to the pegs 28 described above, and ashear-thickening fluid 1230.

An example of a combination of airfoils assembled so as to becircumferentially spaced apart from each other is shown in FIG. 18 . Inthe illustrative embodiment, the airfoil assembly includes at leastthree airfoils 116. The airfoils 116 are each formed identically toinclude the same cavity 122, and the same plurality of radiallyextending walls 128, as described above. The airfoils 116 each include adiffering amount of shear-thickening fluid 130 disposed in the cavities122, as shown in FIG. 18 . The differing amounts of fluid 130 providemistuning of the adjacent airfoils 116 without compromise of theaerodynamic definition of the blades. Such mistuning is especiallybeneficial in embodiments in which the airfoils 116 are utilized in abladed rotor assembly. Although this embodiment includes the airfoil116, any of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816,916, 1016 described above may be arranged in a similar manner. In otherembodiments, the airfoils may alternate between a first airfoil 116including the cavity 122, the plurality of radially extending walls 128,and the fluid 130, as described above, and a second airfoil 116 in whichthe cavity 122 is filled with epoxy putty. This arrangement will alsoprovide mistuning of the adjacent airfoils 116.

A further example of a combination of airfoils assembled so as to becircumferentially spaced apart from each other is shown in FIG. 19 . Inthe illustrative embodiment, the airfoil assembly includes at leastthree airfoils 16, 116, 216. The airfoils 16, 116, 216 are each formedidentically to include the same cavity 22, 122, 222 and the same amountof shear-thickening fluid 30, 130, 230 as described above. The airfoils16, 116, 216 each include a different type of obstructing member 28,128, 228, as shown in FIG. 19 . For example, the first airfoil 116includes the plurality of radially extending walls 128, the secondairfoil 16 includes the plurality of pegs 28, and the third airfoil 216includes the plurality of angled walls 228. The differing obstructingmembers 28, 128, 228 provide mistuning of the adjacent airfoils 16, 116,216 without compromise of the aerodynamic definition of the blades. Suchmistuning is especially beneficial in embodiments in which the airfoils16, 116, 216 are utilized in a bladed rotor assembly. Although thisembodiment includes the airfoils 16, 116, 216, any of the airfoils 16,116, 216, 316, 416, 516, 616, 716, 816, 916, 1016 described above may bearranged in a similar manner.

A further example of a combination of airfoils assembled so as to becircumferentially spaced apart from each other is shown in FIG. 20 . Inthe illustrative embodiment, the airfoil assembly includes at leastthree airfoils 116. The airfoils 116 are each formed identically toinclude the same cavity 122 as described above. A first airfoil 116includes the shear-thickening fluid 130 inside the cavity 122, while anadjacent second airfoil 116 includes an epoxy putty material filling thecavity 122. An airfoil assembly may include alternating airfoils 116 ofairfoils 116 filled with shear-thickening fluid 130 and epoxy putty inthe cavities 122. Although this embodiment includes the airfoils 116,any of the airfoils 16, 116, 216, 316, 416, 516, 616, 716, 816, 916,1016 described above may be arranged in a similar manner.

A method according to another aspect of the present disclosure includesa first operation of providing an airfoil body having a leading edge, atrailing edge opposite the leading edge, a pressure side, and a suctionside opposite the pressure side, and a second operation of forming acavity within the airfoil body. The method further includes a thirdoperation of filling the cavity with a shear-thickening fluid, wherein aviscosity of the shear-thickening fluid increases in response to theairfoil experiencing at least one of an aeromechanic response andvibrations during use of the airfoil. The method further includes afourth operation of arranging at least one obstructing member within thecavity that is configured to obstruct movement of the shear-thickeningfluid within the cavity in response to the viscosity of theshear-thickening fluid increasing so as to dampen the vibrations of theairfoil and reduce negative effects of a dynamic response of theairfoil.

The embodiments described herein provide mode attenuation withoutchanging the aerodynamic shape of the airfoil 16, 116, 216, 316, 416,516, 616, 716, 816, 916, 1016. The design space on the interior of theairfoil 16, 116, 216, 316, 416, 516, 616, 716, 816, 916, 1016 is suchthat the cavity, internal features, and attributes of the shearthickening fluid can be tailored for a particular application, inlet,mission condition, or mode shape. The airfoil 16, 116, 216, 316, 416,516, 616, 716, 816, 916, 1016 described above would potentially reduceweight while passively increasing HCF capability in a difficultenvironment by increasing damping. The pegs, ridges, and walls describedabove could be machined as part of the airfoil pressure and suction sidepanels, while the mesh grid may be produced as a separate layer ormembrane to be inserted or combined with the pressure and suction sidepanels. The location of the cavity could be tailored to particular modesof interest or challenges from the inlet distortion. With differentfluid design, protrusions, locations and other variations, there wouldbe significant ability to tune design to suit various applications. Itmay be possible to have a mesh at the center of the chord and then pegsor baffles at ends, etc. The density and/or viscosity could be tuned fordifferent regions as well.

In the embodiments described above with regard to the airfoils 16, 116,216, 316, 416, 516, 616, 716, 816, 916, 1016, 1116, 1216, theembodiments that include obstructing members that obstruct chord-wisemotion of the shear-thickening fluid are most suitable for responding totorsion or twisting motion of the airfoil 16, 116, 216, 316, 416, 516,616, 716, 816, 916, 1016, 1116, 1216 about a central axis of the airfoilthat extends radially. The embodiments that include obstructing membersthat obstruct through-thickness motion of the shear-thickening fluid aremost suitable for responding to flap or bending motion of the airfoil16, 116, 216, 316, 416, 516, 616, 716, 816, 916, 1016, 1116, 1216 abouta central axis of the airfoil that extends in a direction from theleading edge to the trailing edge.

While the disclosure has been illustrated and described in detail in theforegoing drawings and description, the same is to be considered asexemplary and not restrictive in character, it being understood thatonly illustrative embodiments thereof have been shown and described andthat all changes and modifications that come within the spirit of thedisclosure are desired to be protected.

What is claimed is:
 1. An airfoil for use in a gas turbine engine, theairfoil comprising an airfoil body extending radially outwardly relativeto an axis and configured to interact with gases surrounding the airfoilbody, the airfoil body having a leading edge, a trailing edge oppositethe leading edge, a pressure side, and a suction side opposite thepressure side, the airfoil body formed to define a cavity within theairfoil body, the cavity being defined by a radially outer top surface,a radially inner bottom surface, a first inner side surface, a secondinner side surface, a pressure side inner surface, and a suction sideinner surface, the airfoil body including a shear-thickening fluiddisposed within the cavity, wherein a viscosity of the shear-thickeningfluid increases in response to the airfoil experiencing at least one ofan aeromechanic response and vibrations during use of the airfoil, andat least one obstructing member arranged within the cavity and fixed tothe airfoil body to obstruct movement of the shear-thickening fluidwithin the cavity in response to the viscosity of the shear-thickeningfluid increasing so as to dampen the vibrations of the airfoil andreduce negative effects of a dynamic response of the airfoil, whereinthe at least one obstructing member includes a plurality of pegs thateach extend from the pressure side inner surface to the suction sideinner surface of the cavity and contact the pressure and suction sideinner surfaces.
 2. The airfoil of claim 1, wherein the plurality of pegsincludes at least two rows of pegs, each row including at least twopegs, wherein each row of pegs of the at least two rows of pegs extendsfrom the leading edge to the trailing edge in a direction generallyaxially relative to the axis, wherein each row of pegs of the at leasttwo rows of pegs is spaced apart from an adjacent row of pegs in aradially direction.
 3. The airfoil of claim 1, wherein the airfoil bodyincludes an airfoil root and an airfoil tip spaced apart radiallyoutward from the airfoil root, and wherein the radially outer topsurface of the cavity is located adjacent to the airfoil tip.
 4. Theairfoil of claim 3, wherein the cavity is arranged radially outwardly ofa halfway point of a radial extent of the airfoil body.
 5. A rotorassembly for use in a gas turbine engine, the rotor assembly comprisinga wheel arranged circumferentially about an axis, and a first airfoilextending radially outwardly from the wheel relative to the axis andconfigured to interact with gases surrounding the first airfoil, thefirst airfoil including a first airfoil body extending radiallyoutwardly relative to an axis and configured to interact with gasessurrounding the first airfoil body, the first airfoil body having aleading edge, a trailing edge opposite the leading edge, a pressureside, and a suction side opposite the pressure side, the first airfoilbody formed to define a first cavity within the first airfoil body,wherein the first cavity is defined by a radially outer top surface, aradially inner bottom surface, a first inner side surface, a secondinner side surface, a pressure side surface, and a suction side surface,the first airfoil body including a first shear-thickening fluid disposedwithin the first cavity, wherein a viscosity of the firstshear-thickening fluid increases in response to the first airfoilexperiencing at least one of an aeromechanic response and vibrationsduring use of the airfoil, and at least one first obstructing memberarranged within the first cavity and configured to obstruct movement ofthe first shear-thickening fluid within the first cavity in response tothe viscosity of the first shear-thickening fluid increasing so as todampen the vibrations of the first airfoil and reduce negative effectsof a dynamic response of the first airfoil, wherein the at least onefirst obstructing member includes a plurality of pegs that each extendfrom the pressure side inner surface to the suction side inner surfaceof the cavity and contact the pressure and suction side inner surfaces.6. A method comprising providing an airfoil body having a leading edge,a trailing edge opposite the leading edge, a pressure side, and asuction side opposite the pressure side, forming a cavity within theairfoil body, filling the cavity with a shear-thickening fluid, whereina viscosity of the shear-thickening fluid increases in response to theairfoil experiencing at least one of an aeromechanic response andvibrations during use of the airfoil, and arranging at least oneobstructing member within the cavity that is configured to obstructmovement of the shear-thickening fluid within the cavity in response tothe viscosity of the shear-thickening fluid increasing so as to dampenthe vibrations of the airfoil and reduce negative effects of a dynamicresponse of the airfoil, wherein the at least one obstructing memberincludes a plurality of pegs that each extend from a first side innersurface of the cavity to a second side inner surface of the cavityopposite the first side inner surface and contact the first and secondside inner surfaces.